Hydraulic cylinder



Aug. 18, 1942. l .1. w. ovERBEKE HYDRAULIC CYLINDER Fiied Nov. s, 1939 4 'sheets-sheet s Aug. 18, 1942. J. w; ovERBEKE HYDAULIC CYLINDER Filed Nov. s, 1939 4 Sheet's-A-Sheet 4 mAVNW WGH t u-pelrat.

cPatented Aug. 18, IMZ

John W. Overbke, Annesiie, Md., assignor to The Glenn L. Martin Company, Baltimore,

Application November 3, 1939, SerialNo. 302,709

2 Claims.

The invention relates to hydraulic cylinders.

Various problems arise in the construction and use of hydraulic cylinders. These cylinders are likely to leak at the joints, 'or around the piston. If the cylinder must be movable, as for example if it must be pivoted about one end thereof, there is a problem of furnishing pressure fluid to the cylinder for its operation. The'rate of operation of the cylinder may also be of importance.

The primary object of the present invention is to provide hydraulic cylinder mechanism which overcomes the above and other disadvantages met with in the prior art.

The primary object of the invention is to provide a novel type of joint for securing the ends oula, cylinder, which is liquid-tight and which is easily applied and removed, while still being able to withstand great pressures.` Many hydraulic cylinders today are 'formed of a light metal to achieve a saving in weight. Such metals do not present. adequate surfaces for the reception of threads, since the metals are likely to be relatively soft, and therefore do not hold a threaded joint against high pressures. The present invention provides means for securing the ends 4on cylinders which avoid the use of threads on the cylinder body and thus produce a strong joint capable of withstanding high pressures.

A further object of the invention is to provide, particularly in such a joint, a novel type of sealing member which is adapted to be deformed into tight engagement ywith the surfaces between whichr-it is arranged without the likelihood that it will, be squeezed out-from between these surfaces where parts of the material may break olf and interfere with the operation of the cylinder.

Still another object of the invention is to provide a novel mounting for a hydraulic cylinder which permits the cylinder to turn about an 4o ation of many types of devices it is'desirable that i the pistonshould move rapidly'l for a. considerable part of its stroke, so as to actuate the mechanism quickly, whileat the end of its stroke the piston should move quite slowly so as to avoid shocks. For example, in the movement of a landing gear on an aircraft to retracted position the gear should be retracted most of the y to the air.

way quite quickly, but the last part of its motion should be slow so as to avoid shocks on the parts on which it is mounted; The present invention includes means for automatically reducing the speed of operation towards the ends of the stroke'. In particular it provides cooperating means in the cylinder and piston for throttling -the ow of fluid'into and out of the cylinder towards the end of the stroke, while giving a free ow at other tienes.v

Some cylinders are of the one-Way type, that is the type in which iiuid is admitted on one side only oi' the piston, the other side being exposed Dust in the air which is sucked in when the piston moves in one direction is likely to collect on the cylinder Walls, and may pass by the piston and become mixed with the operating fluid. thus-contaminating it and scoring the piston and cylinder as well as other parts of the system. The present invention is designed to provide means for removing such dust froml Further objects and advantages of the inven-` tion will appear more fully from the description,

axis, and `still feeds pressure fluid thereto without the use of flexible pipes or ther similar elements which have been heretofore used. Particularly the invention'involves a special pivot arrangement in which the fluid is fed in through a fixed pin about which the cylinder is mounted for turning movement.

stm another object of the inventionl is to provides. novel type of sealing ring forl use in hy'- draulicpressure cylinders, which is easy to install on. the piston and which gives altight seal when ini-use,v and has a .long life.

y A further object of the invention is to provide anovel mechanism for regulating the speed of ofthe hydraulic piston. In thev opersealing member; Flg. 6 is a cross-section on the line 6 6 o f particularly when taken in conjunction with the accompanying drawings which form a part thereof. f

In the drawings:

Fig. 1 shows in sideelevation one form of cylinder embodying my invention;

Fig. 2 is a cross-section on the line 2--2 A of Aof Fig. 2, with the piston in retracted position,

and showing in broken lines the piston in eir- Fig. 5 is a detail cross-section through the Fig. 3; l

Fig. 7 shows in side elevation with parts bro- The aluminum layers 24 are relatively soft, and' ken away a modied form of the invention, em-

bodying a one-way piston;

Fig. -8 is a cross-section on the line 8-8 of Fig. 7.

In the form shown' in Figs. 1 to 6, the inven- 5 tion includes a, cylinder 'such as 2'formed of a light alloy, such as the well known-aluminum alloys. Adjacent each end of this piston but spaced slightly inwardly therefrom there is formed on the outside thereof an annular shoulder` 4, or other ferm of stop. Otherwisethe cylinder is of simple cylindrical form. I

Secured on the vright-hand or inner end of the cylinder is a closure block or cylinder end g sion of threadsin the light metal," 'which threads would be likely to be stripped bythe pressure because ofthe comparative softness of the metal of the cylinder. Instead, there is provided a split ring 8 adapted to iit on the outside of the cylinder, and having a surface Ili capable of resting against the inner face of shoulder 4 and an opposed surface I2 parallel to surface III. An

annular ring I4 is adapted to t on the outside 25 of ring 8, and to rest against the shoulder I2. Bolts I5 pass through 'lugs on ring I4 and block 4 to connect the block 8 to the cylinder rend.

In assembling this mechanism, the ring I4 is first slipped over the end of the cylinder, well beyond the shoulder 4. The two portions of ring 8 are then assembled in the position sh wn, and ring I4 is slid back to the position shown in Fig.

3. Theblock 6 is then applied on 'the end of the cylinder, and the bolts are applied and tightened so as to hold thel block 8 in position.

The block 6 isprovided with a-groove I8 into which the end of the cylinder 2 can it. Within this groove is arranged a. sealing ring 20, which is thus pressed between the bottom of the groove and the outer edge of thegcylinder. This ring is shown in detail in Fig. 5. I have found that by utilizing a metallic sealing member composed of a relatively hard metal core coated on both faces with a softer metal it is possible to obtain a fluid tight seal which is strong enough to retain its constitution in spite of the pressure to which it is subjected.` Preferably this seal is composed of 24 ST Alclad, which is a core such as 22 of an aluminum alloy which is relatively hard, coated on both faces with a layer 24 of aluminum.

thus can be deformed to lflt any irregularities in the surface between which they are pressed` The `core 22 atjthe same time prevents the squeezing 55 of the softer aluminum out from between the surfaces, since it in effect anchors the aluminum. Thus there is no danger that the aluminum will be squeezed i'rto the cylinder where it may break I oil' in the form'v of small particles andl interfere 60 with the peration' thereof.

The cylinderisintended to be mounted in a- -f suitable frame having two arms 28 provided with aligned openings therein. Into one of these openings fits a reduced end 28 of a sleeve or 65 trunnion member4 I8. This member is providedA with a large iiange'32 adjacent ,its end 28 which rests against the' inner face of one of Lthe mem- Q bers 28.- The sleeveis also provided at each end with inlet passages 84 and 88 respectively, these '10 being separated by a central wall portion 28.

A Each of the inlet passages is connected Aby transverse passages 40 to an. annular space 42, the

spaces 42 bing formed by three small` projecting annular flanges 44 on the sleeve 80. The 75 O A I a utonlnoves towards the left.

spaces 42 are sealed by suitable sealing members 48.

- 'I'hreaded on the other end of the core or sleeve 30 is a member 48 adapted to fit in the hole in thevother support 25. This member has at its inner end a large ange 50. The block 6 has an extending cylindrical portion 52 through which the pin 38 extends, this cylindrical portion being restrained against lateral movement by the flanged portions 32 and 50, and resting also on the annular flanges 44 both to provide a bearing for the cylindrical portion 52 and to close oif the spaces 4 2. The cylinder is thus mounted for i 'turning movement about its right-hand end on member 5. The block 5 is notthreaded on the@ cylinder end, since this would involve the p rovij .l

lieaxisA of the member 88.

^ 'Ihe block 5 is'also provided with an inlet opening 54 communicating with one of the spaces 42.

Fluid from the opening 54 enters into an elongated tube of reduced cross-section which is mounted in the end block 5.- The other space 42 communicates with a pipe 55 which is rigid with the cylindrical portion 52, and which en- ,ters as at 58 at the other end ,of the cylinder 68. -On` one end is secured the piston 18. The

piston is provided with two ring grooves 12 in which are mounted a novel type ofpacking. Each packing comprises an annular ring I4 preferably of rubber or' some similar elastic material. .The ring has two annular projections 'I8 and 'I8 forming a groove therebetween, -A metal ring 88 fits into this groove and at its other side rests on the end surface of the piston groove 12, so as to hold the ring 14 in place.V The outer annular projection 'i5 is resiliently urged into contact with the wall of the cylinder, and thus keeps a constant pressure thereagainst to seal the piston as it slides in the cylinder. The projections on the two rings are oppositely directed so as to seal the piston upon movement in both directions.

right-haria or inne end 1s a'tube sz,c1osed at its left-hand end and at its right-hand end provided with an inwardly turned portion 84 providing .a reduced'outlet. The opening in-member 84 is slightly, larger than the outside diameter of the projecting fluid inlet 50. As long as' the 4piston,is moving freely in the cylinder, that is.'

from the left towards theright, until the portion 84 approaches, very closely to the end of tube 60, fluid may ow freely. out through tube 80. ,When, however, the tube 60 enters and extends through the opening in member 8,4`f the flowi of fluid. is greatly retarded because it must ow through the small remaining portion of opening 84 from the outside of tube 80 to the inside' thereof, through the tube 82. Therefore the motion will be greatly retarded towards the end of the movement of the piston in the cylinder.

braking effect is obtained as the pis- The piston carries at its left-hand side a ijiange 88, which as it approaches the left-hand end of its movement.. 4

passes into the reduced opening formedby the inwardly projecting ring 88. Itis evident that I1 to 6, is provided.

E n Y 2,293,167 the uid displaced by the piston and escaping through outlet 58 must then pass through the. i

narrow opening between flange 99 and projection 98, which will of course retard the rate of escape 4 of fluid and thus the motion of the piston.

The mechanism is soarranged that Ithe connection to the piston rod may be varied. For

this purpose the endoi' the piston rod is threaded as at 90, and th'ere is iltted thereon an interi nally threaded sleeve `92 which may be held in any given position by a lock .nut 99. The end of the sleeve is reduced to form two extending plates 96. To the outsldesof these plates are connected links 91 which in turn are connected v to the device which is to be moved. Between the two plates extends a link 99 which is intended for manual operation in casethe cylinder should be inoperative for any reason. Links 91 and 96 are both connected to the plates by a single pin It will be evident that as fluid isrsupplied to. one or the`other oi' inlet openings 39, 39 the'piston will be moved in one direction or the other, the fluid exhausting through the other oi Lthe openings.

The form of the invention shown in Figs. I and 8 embodiesnany of the features of that described above, but relates to a one-way cylinder in which fluid is admitted on one side only of the piston.

The cylinder |02 is provided on its right-hand end with a shoulder |94. On the inside of this shoulder is arranged a ring |06, preferably a jsplit ring, having'a shoulder H2. An annular of the cylinder is arranged a sealing member v|2|| similar to that shown in Fig. 5. The cylinder head is thus secured to the cylinder wall without the use o! any threads on the cylinder itself.

The cylinder is mounted to turn about its right-I i hand end in a frame having portions |29 provided with opposed openings therein. 'I'hrough these openings passes a pin"or'sleeve-- |3U, having Lat one end a flange |91 adapted to engage the outside oi' one oi portions |29, and held inposition at its other end by a nut |33 engaging the other member |29. The sleeve is provided with a bore |99 which communicates through radial apertures |90 with a space |92 formed in a cylindrical projection |52,-of the cylinder end portion ||l9 through which the core |99 extends. A passage in when the piston movestothe right will bring in dust and dirt which will slip by the piston and thus contaminate the iluid. This results in scoring ofthe different parts of the system and in other damage. To avoid this danger, the cylinder end |62 is provided withja series of holes or passages |63 which lead into an annular groove |65 filled with a suitable filtering material such as soft metal wool which may be coated with an oily or greasy liquid to catch dust particles. The groove |65 is closedby a sheet metal sleeve |61 provided with a plurality of air holes |68 therein to permit the air to enter and leave the filter.

Obviously with the above mechanism the admission oi' uid under pressure into opening |36 will move the piston to the left. The device is of course used with some mechanism which either by gravity or by spring devices normally urges the piston to the right. 'I'hus when the pressure is released, the piston will be moved to the right under the action of the opposing force.

. While I have described herein some embodi- *l ments of my invention I wish it to be understood that I do not intend to limit myself thereby except n v within the scope of the appended claims.

I claim: l K

l. In hydraulic cylinder mechanism, a frame having opposed openings therein, a sleeve member mounted in said openings, said sleeve member having passages opening into the ends thereof through said openings, a hydraulic cylinder having a head portion provided with a cylindrical part surrounding said sleeve and mounted for turning movement thereon between said lframe members, said sleeve being provided with three spaced annular flanges forming withV said cylindrical portion a plurality of annular chambers, passages connecting said Aopenings in said sleeve to said annular chambers, a passage in said cylinder head portionv connecting one of said annular chambers to the interior of the cylinder. and means mounted on said cylinder connecting the other annular chamberto the other end oi the cylinder.

2. In hydraulic cylinderv mechanism,. a frame having opposed openings therein, a' sleeve member mounted in said openings, said sleeve member having passages opening into the ends thereof `through said openings, a hydraulic cylinder having a head portion provided with/a cylindrical part surrounding said sleeve 'and `Vmounted for turning movement thereonbetween said frame members, said sleeve having three small annular flanges thereon engaging the inner face vof said cylindrical portion and forming therewith a plurality of annular chambers, passages connecting |99 connects the chamber A|92 to the interior of 1 to 6, except that only a single sealing ring |19,

identicalwith the right-hand sealing ring of F188.

The other end of the cylinder is not subjected to hydraulic forces and therefore there is no necessity for the use of a special connection. The

cylinder end member |92 is merely threaded on the end of the cylinder. The piston rod |99 extends through a suitable -sleeve |99 therein, and v said openings in said eeve to respective ones of said annular chambe a passage in said cylinder head portion connecting one of said annular chambers to the interior of the cylinder, means mounted on said cylinder connecting the other annular chamber to the other end of the cylin- Tder, said sleeve being formed also with a large iiange adjacent one end between the ycorresponding end of the'lcylindrical part of the head portion and the frame adjacent one opening, and a member threaded externally` to the other end o! 'said sleeve within the adjacent frame opening.

'7o said'member'having a` large flange adjacent its inner end arranged between the corresponding end of the cylindrical' part of the head portion and the trame. d 

